all: replace internal rand shim with math/rand/v2

lapack/testlapack/dpttrs.go

@@ -6,10 +6,10 @@ package testlapack
 
 import (
 	"fmt"
+	"math/rand/v2"
 	"testing"
 
 	"gonum.org/v1/gonum/blas/blas64"
-	"gonum.org/v1/gonum/internal/rand"
 	"gonum.org/v1/gonum/lapack"
 )
 
@@ -20,7 +20,7 @@ type Dpttrser interface {
 }
 
 func DpttrsTest(t *testing.T, impl Dpttrser) {
-	rnd := rand.New(rand.NewSource(1))
+	rnd := rand.New(rand.NewPCG(1, 1))
 	for _, n := range []int{0, 1, 2, 3, 4, 5, 10, 20, 50, 51, 52, 53, 54, 100} {
 		for _, nrhs := range []int{0, 1, 2, 3, 4, 5, 10, 20, 50} {
 			for _, ldb := range []int{max(1, nrhs), nrhs + 3} {